Keratoconus Treatment
Keratoconus is a fairly uncommon condition that affects the cornea (the transparent window at the front of the eye). Keratoconus causes changes within the structure of the cornea making it weaken and thin resulting in a 'cone shaped' forward bulge. Keratoconus leads to myopia (short sight) and, if the steepening is uneven, also astigmatism (distortion of vision). With Keratoconus, visual distortion can become difficult to correct with spectacles, although contact lenses (usually rigid) can provide more functional visual performance.
Please click on our Keratoconus booklet or the link below to find out more about the Keratoconus condition and how Accuvision can help you.
Keratoconus Information Booklet
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What is Keratoconus?
Keratoconus is a congenital disease of the cornea (autosomal dominant or autosomal recessive) and it belongs to the large group of hereditary corneal dystrophies.
The disease is characterised by thinning and conus-like protrusion of the cornea. This is due to alterations that cause weakening of the corneal structure.
At first, the protrusion occurs in the inferior parts (lower half) but later on it also affects the central part of the cornea. Keratoconus mostly happens to be bilateral but often the progression is asymmetrical.
Symptoms of Keratoconus
Keratoconus symptoms usually start during puberty or early adolescence. As the keratoconus progresses it leads to myopia (short sight) and, if the steepening of the cornea is uneven, also astigmatism (distortion of vision). In most cases patients realise a decrease or blurring in vision, or an increasing myopia with a significant progression of astigmatism. Patients usually seek corrective lenses at first for driving or reading. Keratoconus at this stage is difficult to differentiate from other more common vision defects. The incidence of keratoconus in the general population is reported to be about 1 in 2000.
Keratoconus is commonly associated with other health disorders. Eye conditions include; allergic eye disease, retinitis pigmentosa, ocular rosacea, cone/rod dystrophy and corneal granular dystrophy. Other bodily conditions would include eczema or hayfever, Down's Syndrome, and connective tissue disorders. Keratoconus has also been linked to forms of eye trauma including contact lens wear and eye rubbing. Diabetes has been shown to increase the severity of the condition.
"Having completed Topography Guided Ablation and Corneal Collagen Cross-linking on both eyes, I am now 20:20 in the left eye after 7 weeks and my right eye is on course for a similar outcome." - Nick Pryce Jones
Possible Treatment Options For Keratoconus
There is no cure for keratoconus and treatment is therefore aimed at optical improvement. Depending on the degree of corneal bulging, (ectasia) thinning of the cornea and resultant astigmatism a number of options can be considered:
Contact Lenses
In advancing cases of keratoconus, rigid (hard) contact lenses help to improve visual acuity, yet they cannot stop the progression of the condition.
Corneal Ring Segment Insert (Intacs)
Clear plastic segments are placed into the cornea (pictured left). Intacs typically only partially correct the optical defect present, so additional optical aids or surgical intervention may be required to obtain full visual correction.
Corneal Transplantation
Up until a few years ago, the only therapeutic option for vision restoration in advanced cases of keratoconus was corneal transplantation (penetrating keratoplasty) to achieve better vision.
Corneal Collagen Cross-Linking
A new minimally invasive procedure called Corneal Collagen Cross-linking with Riboflavin (C3-R®) has now been developed. This treatment uses a combination of Riboflavin drops and ultra violet light that react with the tissues in the cornea, strengthening them by creating more 'cross-linking' among them. The resulting increased stiffness and rigidity of the cornea stabilises ectasia. Patients who previously had progressive ectasia have now been treated and followed for up to five years without evidence of any further change in their condition.
"The quality of vision that has been achieved has far exceeded my expectation, and the less developed eye already has remarkably good vision only 2 weeks after surgery." - Peter De'Ath
Corneal Collagen Cross-Linking (C3R®) at Accuvision
The aim of this treatment is to stabilise the cornea and prevent the progression of keratoconus.
The main structure of the corneal tissue (stroma) consists of single collagen fibres which are linked. The treatment of keratoconus with collagen cross-linking is based on a significant stiffening of the corneal stroma due to photochemical cross-linking of the single collagen fibres. Therefore the single fibres form a "denser network" which leads to an increase in the overall stability of the cornea. This procedure is performed under topical anaesthesia.
After an epithelium abrasion (corneal scraping), Riboflavin (vitamin B) drops are applied to the corneal surface over a period of 30 minutes and the cornea is then exposed to 365nm UV for a 30 minute period thereafter.
After the treatment a bandage contact lens is applied and a combination of a steroid and antibiotic drop is prescribed. During the follow up assessments of eyes treated with collagen cross-linking, very few patients showed further progression.
In approximately 80% of the patients a regression of the maximal K-values (regression of the keratoconus) has been observed. Post surgical corrected visual acuity improvement of 1 to 2 Snellen lines can be expected. No unwanted side effects such as opacification of the lens or loss of endothelial cells has been reported.
Only during the first 2 to 3 months after the cross-linking has a minor superficial corneal haze been observed. Generally this minor haze disappears without any treatment, but a supportive therapy with soothing ointment or with local steroid drops (i.e. FML or Prednisone) can be prescribed under supervision.
Accuwave™ Topography Guided Custom Ablation Treatment for Keratoconus (T-CAT)
In addition to 'simple' cross-linking, Accuvision can offer selected patients combined corneal collagen crosslinking with corneal laser re-shaping.
This advanced treatment is designed to improve central corneal symmetry, without attempting to correct other spherical, or regular astigmatic, optical defects.
Advanced Topography Guided (T-CAT) laser treatment is kept to a small degree of tissue ablation, with the maximum depth of tissue loss typically less than 50 microns. Corneal Collagen Cross-linking with Riboflavin (C3-R®) treatment is applied immediately after the laser treatment. Any spherical or regular astigmatic, optical defect remaining after the combined Accuwave™ T-CAT treatment with Corneal Collagen Cross-linking can be corrected subsequently by contact lens wear or by phakic intra-ocular lens implantation.
"I achieved 20:20 vision without lenses, which is a fantastic result having had a -3.00 dioptre of astigmatism. The NHS told me there was nothing they could do but prescribe glasses." - Christopher Jackson
Potential Risks of C3-R Treatment for Keratoconus
UV light is known to be damaging to cells, and the keratoconus treatment causes the stromal cells (keratocytes) in the outer layers of the treated parts of the cornea to die. However, these cells are replaced by new keratocytes which migrate from untreated parts of the cornea into the central area over a period of some months after the keratoconus C3-R® treatment. In theory the UV light could be damaging to the inner endothelial cell layer of the cornea, and this is why the corneal thickness needs to be at least 350 microns if a standard keratoconus C3-R® treatment is to be undertaken. In clinical studies carried out so far, no evidence of damage to the endothelial cell layer has been documented. Although UV is potentially damaging to the lens and retina, it is believed that the riboflavin blocks the UV transmission to an extent that no measurable damage will occur. At present the long term effects of the keratoconus treatment are unknown.
Results:
- All patients exhibited a reduction in irregular astigmatism
- Mean improvement in topographical asymmetry was 7.8D
- Two thirds of patients had improved Best Corrected Visual Acuity
- No patients lost Best Corrected Visual Acuity
| Patient | Difference along steepest meridian: | Gain/Loss BCVA (Snellen Lines) |
||
|---|---|---|---|---|
| Pre-Op | Post-Op | Improvement | ||
|
Using C3-R® and Topography Guided Custom Ablation our results show significant reduction in pre-op irregular astigmatism. D = Dioptre. |
||||
| SMR | 8D | 2.5D | 5.5D | +1 |
| SML | 13D | 3D | 10D | = |
| MGR | 15D | 2D | 13D | +3 |
| GCR | 3D | 1.5D | 1.5D | +1/2 |
| GCL | 8.5D | 0.5D | 8D | +1 |
| SBR | 5D | 3D | 2D | = |
| SBL | 8D | 3.5D | 4.5D | +1 |
| PBR | 7D | 5D | 2D | = |
| PBL | 13D | 7D | 6D | +2 |
| IOR | 18D | 4D | 14D | +1 |
| IOL | 21D | 11D | 10D | +1/2 |
| PJR | 18D | 4D | 14D | +4 |
| PJL | 10D | 2D | 8D | +1 |
| JOR | 17D | 6D | 11D | = |
| JOL | 14.5D | 2.5D | 12D | = |
| MWR | 11D | 6D | 5D | +1 |
| LSR | 6D | 2D | 4D | = |
| PPR | 9D | 0D | 9D | +1 |
| PPL | 7D | 3D | 4D | = |
Accuvision Lifetime Aftercare
Due to the progressive nature of keratoconus, lifetime monitoring and care is essential.
The corneal surface and biomechanical properties are first surgically stabilised using a combination of advanced Topography Guided Laser treatment combined with Riboflavin Corneal Collagen Cross-linking. The resultant topography (profile) is relatively normalised and more symmetric. Hence post operative contact lens fitting with improved tolerance becomes a viable option. The focus when fitting a keratoconic eye with a contact lens is on stable visual acuity with minimum long term corneal stress and influence.
Often, there are many questions that are considered when a contact lens fit is mentioned post operatively. Some of the most common questions are addressed below:
Why can't I wear glasses instead of contact lenses?
It is possible to wear glasses, however the visual acuity can be limited. Though the corneal surface has been stabilised as much as possible, it is still relatively irregular when compared to a 'normal' eye. This means that a contact lens offers a much better quality of vision.
Why can't I wear soft contact lenses?
Soft lenses mould to the shape of the eye and therefore mirror rather than mask any irregularities in the corneal surface. A rigid lens creates a smooth surface that allows tears to flow more freely and therefore improves oxygen accessibility to the cornea. This offers the additional benefit of a healthier eye even with long term or extended wear.
I have tried hard (Rigid Gas Permeable or RGP) lenses in the past and they were uncomfortable or gave poor vision or were difficult to handle. Why would this be different now?
After treatment, the corneal surface is much more regular and therefore more responsive to a lens. This means that since the lens fit is enhanced, vision is improved and therefore patient satisfaction is much more likely. Additionally, the Accuvision Team is highly experienced and specialised in complex contact lens fits and this will ensure that patients are taught how to handle, care for and manage lenses on a personalised basis.
